One User Controls Over Half of Bitcoin Mining – and That's a Security Risk

For the first time in its history, a single user has begun to provide over half the computational power used to mine the digital coins. But with much of Bitcoin's security stemming from its decentralised structure, that could prove a large security risk.

Ars Technica reports that researchers from Cornell University have noticed that a single mining pool contributes over 51 per cent of the currency's hashing (the cryptographic process required to mint Bitcoin) repeatedly, for periods of 12 hours or more. The user is GHash, which proudly names itself the "#1 Crypto & Bitcoin Mining Pool." Clearly it's not lying.

While it might not sound too much of a problem on the face of it, such computational power could be damaging for the currency. Quirks of Bitcoin mean that those who control over 50 per cent of Bitcoin mining have the ability to spend the same coins twice, are able to reject competing miners' transactions, and even extort higher fees from people with large holdings. And if things get really nasty, a 51-per-center could wage a DDoS attack against the rest of the network.

While GHash has only maintained majority control for up to 12 hours at time, that figure is recent; in the past, it had only managed to for minutes or hours. In others words, its control is on the rise and, speaking to Ars Technica, the researchers suggest that even 12 hours would be enough for those aforementioned security threats to become a realistic threat.